forked from Qortal/Brooklyn
You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
551 lines
16 KiB
551 lines
16 KiB
// SPDX-License-Identifier: GPL-2.0 |
|
/* Copyright (C) B.A.T.M.A.N. contributors: |
|
* |
|
* Martin Hundebøll <[email protected]> |
|
*/ |
|
|
|
#include "fragmentation.h" |
|
#include "main.h" |
|
|
|
#include <linux/atomic.h> |
|
#include <linux/byteorder/generic.h> |
|
#include <linux/errno.h> |
|
#include <linux/etherdevice.h> |
|
#include <linux/gfp.h> |
|
#include <linux/if_ether.h> |
|
#include <linux/jiffies.h> |
|
#include <linux/lockdep.h> |
|
#include <linux/minmax.h> |
|
#include <linux/netdevice.h> |
|
#include <linux/skbuff.h> |
|
#include <linux/slab.h> |
|
#include <linux/spinlock.h> |
|
#include <linux/string.h> |
|
#include <uapi/linux/batadv_packet.h> |
|
|
|
#include "hard-interface.h" |
|
#include "originator.h" |
|
#include "routing.h" |
|
#include "send.h" |
|
|
|
/** |
|
* batadv_frag_clear_chain() - delete entries in the fragment buffer chain |
|
* @head: head of chain with entries. |
|
* @dropped: whether the chain is cleared because all fragments are dropped |
|
* |
|
* Free fragments in the passed hlist. Should be called with appropriate lock. |
|
*/ |
|
static void batadv_frag_clear_chain(struct hlist_head *head, bool dropped) |
|
{ |
|
struct batadv_frag_list_entry *entry; |
|
struct hlist_node *node; |
|
|
|
hlist_for_each_entry_safe(entry, node, head, list) { |
|
hlist_del(&entry->list); |
|
|
|
if (dropped) |
|
kfree_skb(entry->skb); |
|
else |
|
consume_skb(entry->skb); |
|
|
|
kfree(entry); |
|
} |
|
} |
|
|
|
/** |
|
* batadv_frag_purge_orig() - free fragments associated to an orig |
|
* @orig_node: originator to free fragments from |
|
* @check_cb: optional function to tell if an entry should be purged |
|
*/ |
|
void batadv_frag_purge_orig(struct batadv_orig_node *orig_node, |
|
bool (*check_cb)(struct batadv_frag_table_entry *)) |
|
{ |
|
struct batadv_frag_table_entry *chain; |
|
u8 i; |
|
|
|
for (i = 0; i < BATADV_FRAG_BUFFER_COUNT; i++) { |
|
chain = &orig_node->fragments[i]; |
|
spin_lock_bh(&chain->lock); |
|
|
|
if (!check_cb || check_cb(chain)) { |
|
batadv_frag_clear_chain(&chain->fragment_list, true); |
|
chain->size = 0; |
|
} |
|
|
|
spin_unlock_bh(&chain->lock); |
|
} |
|
} |
|
|
|
/** |
|
* batadv_frag_size_limit() - maximum possible size of packet to be fragmented |
|
* |
|
* Return: the maximum size of payload that can be fragmented. |
|
*/ |
|
static int batadv_frag_size_limit(void) |
|
{ |
|
int limit = BATADV_FRAG_MAX_FRAG_SIZE; |
|
|
|
limit -= sizeof(struct batadv_frag_packet); |
|
limit *= BATADV_FRAG_MAX_FRAGMENTS; |
|
|
|
return limit; |
|
} |
|
|
|
/** |
|
* batadv_frag_init_chain() - check and prepare fragment chain for new fragment |
|
* @chain: chain in fragments table to init |
|
* @seqno: sequence number of the received fragment |
|
* |
|
* Make chain ready for a fragment with sequence number "seqno". Delete existing |
|
* entries if they have an "old" sequence number. |
|
* |
|
* Caller must hold chain->lock. |
|
* |
|
* Return: true if chain is empty and the caller can just insert the new |
|
* fragment without searching for the right position. |
|
*/ |
|
static bool batadv_frag_init_chain(struct batadv_frag_table_entry *chain, |
|
u16 seqno) |
|
{ |
|
lockdep_assert_held(&chain->lock); |
|
|
|
if (chain->seqno == seqno) |
|
return false; |
|
|
|
if (!hlist_empty(&chain->fragment_list)) |
|
batadv_frag_clear_chain(&chain->fragment_list, true); |
|
|
|
chain->size = 0; |
|
chain->seqno = seqno; |
|
|
|
return true; |
|
} |
|
|
|
/** |
|
* batadv_frag_insert_packet() - insert a fragment into a fragment chain |
|
* @orig_node: originator that the fragment was received from |
|
* @skb: skb to insert |
|
* @chain_out: list head to attach complete chains of fragments to |
|
* |
|
* Insert a new fragment into the reverse ordered chain in the right table |
|
* entry. The hash table entry is cleared if "old" fragments exist in it. |
|
* |
|
* Return: true if skb is buffered, false on error. If the chain has all the |
|
* fragments needed to merge the packet, the chain is moved to the passed head |
|
* to avoid locking the chain in the table. |
|
*/ |
|
static bool batadv_frag_insert_packet(struct batadv_orig_node *orig_node, |
|
struct sk_buff *skb, |
|
struct hlist_head *chain_out) |
|
{ |
|
struct batadv_frag_table_entry *chain; |
|
struct batadv_frag_list_entry *frag_entry_new = NULL, *frag_entry_curr; |
|
struct batadv_frag_list_entry *frag_entry_last = NULL; |
|
struct batadv_frag_packet *frag_packet; |
|
u8 bucket; |
|
u16 seqno, hdr_size = sizeof(struct batadv_frag_packet); |
|
bool ret = false; |
|
|
|
/* Linearize packet to avoid linearizing 16 packets in a row when doing |
|
* the later merge. Non-linear merge should be added to remove this |
|
* linearization. |
|
*/ |
|
if (skb_linearize(skb) < 0) |
|
goto err; |
|
|
|
frag_packet = (struct batadv_frag_packet *)skb->data; |
|
seqno = ntohs(frag_packet->seqno); |
|
bucket = seqno % BATADV_FRAG_BUFFER_COUNT; |
|
|
|
frag_entry_new = kmalloc(sizeof(*frag_entry_new), GFP_ATOMIC); |
|
if (!frag_entry_new) |
|
goto err; |
|
|
|
frag_entry_new->skb = skb; |
|
frag_entry_new->no = frag_packet->no; |
|
|
|
/* Select entry in the "chain table" and delete any prior fragments |
|
* with another sequence number. batadv_frag_init_chain() returns true, |
|
* if the list is empty at return. |
|
*/ |
|
chain = &orig_node->fragments[bucket]; |
|
spin_lock_bh(&chain->lock); |
|
if (batadv_frag_init_chain(chain, seqno)) { |
|
hlist_add_head(&frag_entry_new->list, &chain->fragment_list); |
|
chain->size = skb->len - hdr_size; |
|
chain->timestamp = jiffies; |
|
chain->total_size = ntohs(frag_packet->total_size); |
|
ret = true; |
|
goto out; |
|
} |
|
|
|
/* Find the position for the new fragment. */ |
|
hlist_for_each_entry(frag_entry_curr, &chain->fragment_list, list) { |
|
/* Drop packet if fragment already exists. */ |
|
if (frag_entry_curr->no == frag_entry_new->no) |
|
goto err_unlock; |
|
|
|
/* Order fragments from highest to lowest. */ |
|
if (frag_entry_curr->no < frag_entry_new->no) { |
|
hlist_add_before(&frag_entry_new->list, |
|
&frag_entry_curr->list); |
|
chain->size += skb->len - hdr_size; |
|
chain->timestamp = jiffies; |
|
ret = true; |
|
goto out; |
|
} |
|
|
|
/* store current entry because it could be the last in list */ |
|
frag_entry_last = frag_entry_curr; |
|
} |
|
|
|
/* Reached the end of the list, so insert after 'frag_entry_last'. */ |
|
if (likely(frag_entry_last)) { |
|
hlist_add_behind(&frag_entry_new->list, &frag_entry_last->list); |
|
chain->size += skb->len - hdr_size; |
|
chain->timestamp = jiffies; |
|
ret = true; |
|
} |
|
|
|
out: |
|
if (chain->size > batadv_frag_size_limit() || |
|
chain->total_size != ntohs(frag_packet->total_size) || |
|
chain->total_size > batadv_frag_size_limit()) { |
|
/* Clear chain if total size of either the list or the packet |
|
* exceeds the maximum size of one merged packet. Don't allow |
|
* packets to have different total_size. |
|
*/ |
|
batadv_frag_clear_chain(&chain->fragment_list, true); |
|
chain->size = 0; |
|
} else if (ntohs(frag_packet->total_size) == chain->size) { |
|
/* All fragments received. Hand over chain to caller. */ |
|
hlist_move_list(&chain->fragment_list, chain_out); |
|
chain->size = 0; |
|
} |
|
|
|
err_unlock: |
|
spin_unlock_bh(&chain->lock); |
|
|
|
err: |
|
if (!ret) { |
|
kfree(frag_entry_new); |
|
kfree_skb(skb); |
|
} |
|
|
|
return ret; |
|
} |
|
|
|
/** |
|
* batadv_frag_merge_packets() - merge a chain of fragments |
|
* @chain: head of chain with fragments |
|
* |
|
* Expand the first skb in the chain and copy the content of the remaining |
|
* skb's into the expanded one. After doing so, clear the chain. |
|
* |
|
* Return: the merged skb or NULL on error. |
|
*/ |
|
static struct sk_buff * |
|
batadv_frag_merge_packets(struct hlist_head *chain) |
|
{ |
|
struct batadv_frag_packet *packet; |
|
struct batadv_frag_list_entry *entry; |
|
struct sk_buff *skb_out; |
|
int size, hdr_size = sizeof(struct batadv_frag_packet); |
|
bool dropped = false; |
|
|
|
/* Remove first entry, as this is the destination for the rest of the |
|
* fragments. |
|
*/ |
|
entry = hlist_entry(chain->first, struct batadv_frag_list_entry, list); |
|
hlist_del(&entry->list); |
|
skb_out = entry->skb; |
|
kfree(entry); |
|
|
|
packet = (struct batadv_frag_packet *)skb_out->data; |
|
size = ntohs(packet->total_size) + hdr_size; |
|
|
|
/* Make room for the rest of the fragments. */ |
|
if (pskb_expand_head(skb_out, 0, size - skb_out->len, GFP_ATOMIC) < 0) { |
|
kfree_skb(skb_out); |
|
skb_out = NULL; |
|
dropped = true; |
|
goto free; |
|
} |
|
|
|
/* Move the existing MAC header to just before the payload. (Override |
|
* the fragment header.) |
|
*/ |
|
skb_pull(skb_out, hdr_size); |
|
skb_out->ip_summed = CHECKSUM_NONE; |
|
memmove(skb_out->data - ETH_HLEN, skb_mac_header(skb_out), ETH_HLEN); |
|
skb_set_mac_header(skb_out, -ETH_HLEN); |
|
skb_reset_network_header(skb_out); |
|
skb_reset_transport_header(skb_out); |
|
|
|
/* Copy the payload of the each fragment into the last skb */ |
|
hlist_for_each_entry(entry, chain, list) { |
|
size = entry->skb->len - hdr_size; |
|
skb_put_data(skb_out, entry->skb->data + hdr_size, size); |
|
} |
|
|
|
free: |
|
/* Locking is not needed, because 'chain' is not part of any orig. */ |
|
batadv_frag_clear_chain(chain, dropped); |
|
return skb_out; |
|
} |
|
|
|
/** |
|
* batadv_frag_skb_buffer() - buffer fragment for later merge |
|
* @skb: skb to buffer |
|
* @orig_node_src: originator that the skb is received from |
|
* |
|
* Add fragment to buffer and merge fragments if possible. |
|
* |
|
* There are three possible outcomes: 1) Packet is merged: Return true and |
|
* set *skb to merged packet; 2) Packet is buffered: Return true and set *skb |
|
* to NULL; 3) Error: Return false and free skb. |
|
* |
|
* Return: true when the packet is merged or buffered, false when skb is not |
|
* used. |
|
*/ |
|
bool batadv_frag_skb_buffer(struct sk_buff **skb, |
|
struct batadv_orig_node *orig_node_src) |
|
{ |
|
struct sk_buff *skb_out = NULL; |
|
struct hlist_head head = HLIST_HEAD_INIT; |
|
bool ret = false; |
|
|
|
/* Add packet to buffer and table entry if merge is possible. */ |
|
if (!batadv_frag_insert_packet(orig_node_src, *skb, &head)) |
|
goto out_err; |
|
|
|
/* Leave if more fragments are needed to merge. */ |
|
if (hlist_empty(&head)) |
|
goto out; |
|
|
|
skb_out = batadv_frag_merge_packets(&head); |
|
if (!skb_out) |
|
goto out_err; |
|
|
|
out: |
|
ret = true; |
|
out_err: |
|
*skb = skb_out; |
|
return ret; |
|
} |
|
|
|
/** |
|
* batadv_frag_skb_fwd() - forward fragments that would exceed MTU when merged |
|
* @skb: skb to forward |
|
* @recv_if: interface that the skb is received on |
|
* @orig_node_src: originator that the skb is received from |
|
* |
|
* Look up the next-hop of the fragments payload and check if the merged packet |
|
* will exceed the MTU towards the next-hop. If so, the fragment is forwarded |
|
* without merging it. |
|
* |
|
* Return: true if the fragment is consumed/forwarded, false otherwise. |
|
*/ |
|
bool batadv_frag_skb_fwd(struct sk_buff *skb, |
|
struct batadv_hard_iface *recv_if, |
|
struct batadv_orig_node *orig_node_src) |
|
{ |
|
struct batadv_priv *bat_priv = netdev_priv(recv_if->soft_iface); |
|
struct batadv_orig_node *orig_node_dst; |
|
struct batadv_neigh_node *neigh_node = NULL; |
|
struct batadv_frag_packet *packet; |
|
u16 total_size; |
|
bool ret = false; |
|
|
|
packet = (struct batadv_frag_packet *)skb->data; |
|
orig_node_dst = batadv_orig_hash_find(bat_priv, packet->dest); |
|
if (!orig_node_dst) |
|
goto out; |
|
|
|
neigh_node = batadv_find_router(bat_priv, orig_node_dst, recv_if); |
|
if (!neigh_node) |
|
goto out; |
|
|
|
/* Forward the fragment, if the merged packet would be too big to |
|
* be assembled. |
|
*/ |
|
total_size = ntohs(packet->total_size); |
|
if (total_size > neigh_node->if_incoming->net_dev->mtu) { |
|
batadv_inc_counter(bat_priv, BATADV_CNT_FRAG_FWD); |
|
batadv_add_counter(bat_priv, BATADV_CNT_FRAG_FWD_BYTES, |
|
skb->len + ETH_HLEN); |
|
|
|
packet->ttl--; |
|
batadv_send_unicast_skb(skb, neigh_node); |
|
ret = true; |
|
} |
|
|
|
out: |
|
batadv_orig_node_put(orig_node_dst); |
|
batadv_neigh_node_put(neigh_node); |
|
return ret; |
|
} |
|
|
|
/** |
|
* batadv_frag_create() - create a fragment from skb |
|
* @net_dev: outgoing device for fragment |
|
* @skb: skb to create fragment from |
|
* @frag_head: header to use in new fragment |
|
* @fragment_size: size of new fragment |
|
* |
|
* Split the passed skb into two fragments: A new one with size matching the |
|
* passed mtu and the old one with the rest. The new skb contains data from the |
|
* tail of the old skb. |
|
* |
|
* Return: the new fragment, NULL on error. |
|
*/ |
|
static struct sk_buff *batadv_frag_create(struct net_device *net_dev, |
|
struct sk_buff *skb, |
|
struct batadv_frag_packet *frag_head, |
|
unsigned int fragment_size) |
|
{ |
|
unsigned int ll_reserved = LL_RESERVED_SPACE(net_dev); |
|
unsigned int tailroom = net_dev->needed_tailroom; |
|
struct sk_buff *skb_fragment; |
|
unsigned int header_size = sizeof(*frag_head); |
|
unsigned int mtu = fragment_size + header_size; |
|
|
|
skb_fragment = dev_alloc_skb(ll_reserved + mtu + tailroom); |
|
if (!skb_fragment) |
|
goto err; |
|
|
|
skb_fragment->priority = skb->priority; |
|
|
|
/* Eat the last mtu-bytes of the skb */ |
|
skb_reserve(skb_fragment, ll_reserved + header_size); |
|
skb_split(skb, skb_fragment, skb->len - fragment_size); |
|
|
|
/* Add the header */ |
|
skb_push(skb_fragment, header_size); |
|
memcpy(skb_fragment->data, frag_head, header_size); |
|
|
|
err: |
|
return skb_fragment; |
|
} |
|
|
|
/** |
|
* batadv_frag_send_packet() - create up to 16 fragments from the passed skb |
|
* @skb: skb to create fragments from |
|
* @orig_node: final destination of the created fragments |
|
* @neigh_node: next-hop of the created fragments |
|
* |
|
* Return: the netdev tx status or a negative errno code on a failure |
|
*/ |
|
int batadv_frag_send_packet(struct sk_buff *skb, |
|
struct batadv_orig_node *orig_node, |
|
struct batadv_neigh_node *neigh_node) |
|
{ |
|
struct net_device *net_dev = neigh_node->if_incoming->net_dev; |
|
struct batadv_priv *bat_priv; |
|
struct batadv_hard_iface *primary_if = NULL; |
|
struct batadv_frag_packet frag_header; |
|
struct sk_buff *skb_fragment; |
|
unsigned int mtu = net_dev->mtu; |
|
unsigned int header_size = sizeof(frag_header); |
|
unsigned int max_fragment_size, num_fragments; |
|
int ret; |
|
|
|
/* To avoid merge and refragmentation at next-hops we never send |
|
* fragments larger than BATADV_FRAG_MAX_FRAG_SIZE |
|
*/ |
|
mtu = min_t(unsigned int, mtu, BATADV_FRAG_MAX_FRAG_SIZE); |
|
max_fragment_size = mtu - header_size; |
|
|
|
if (skb->len == 0 || max_fragment_size == 0) |
|
return -EINVAL; |
|
|
|
num_fragments = (skb->len - 1) / max_fragment_size + 1; |
|
max_fragment_size = (skb->len - 1) / num_fragments + 1; |
|
|
|
/* Don't even try to fragment, if we need more than 16 fragments */ |
|
if (num_fragments > BATADV_FRAG_MAX_FRAGMENTS) { |
|
ret = -EAGAIN; |
|
goto free_skb; |
|
} |
|
|
|
bat_priv = orig_node->bat_priv; |
|
primary_if = batadv_primary_if_get_selected(bat_priv); |
|
if (!primary_if) { |
|
ret = -EINVAL; |
|
goto free_skb; |
|
} |
|
|
|
/* Create one header to be copied to all fragments */ |
|
frag_header.packet_type = BATADV_UNICAST_FRAG; |
|
frag_header.version = BATADV_COMPAT_VERSION; |
|
frag_header.ttl = BATADV_TTL; |
|
frag_header.seqno = htons(atomic_inc_return(&bat_priv->frag_seqno)); |
|
frag_header.reserved = 0; |
|
frag_header.no = 0; |
|
frag_header.total_size = htons(skb->len); |
|
|
|
/* skb->priority values from 256->263 are magic values to |
|
* directly indicate a specific 802.1d priority. This is used |
|
* to allow 802.1d priority to be passed directly in from VLAN |
|
* tags, etc. |
|
*/ |
|
if (skb->priority >= 256 && skb->priority <= 263) |
|
frag_header.priority = skb->priority - 256; |
|
else |
|
frag_header.priority = 0; |
|
|
|
ether_addr_copy(frag_header.orig, primary_if->net_dev->dev_addr); |
|
ether_addr_copy(frag_header.dest, orig_node->orig); |
|
|
|
/* Eat and send fragments from the tail of skb */ |
|
while (skb->len > max_fragment_size) { |
|
/* The initial check in this function should cover this case */ |
|
if (unlikely(frag_header.no == BATADV_FRAG_MAX_FRAGMENTS - 1)) { |
|
ret = -EINVAL; |
|
goto put_primary_if; |
|
} |
|
|
|
skb_fragment = batadv_frag_create(net_dev, skb, &frag_header, |
|
max_fragment_size); |
|
if (!skb_fragment) { |
|
ret = -ENOMEM; |
|
goto put_primary_if; |
|
} |
|
|
|
batadv_inc_counter(bat_priv, BATADV_CNT_FRAG_TX); |
|
batadv_add_counter(bat_priv, BATADV_CNT_FRAG_TX_BYTES, |
|
skb_fragment->len + ETH_HLEN); |
|
ret = batadv_send_unicast_skb(skb_fragment, neigh_node); |
|
if (ret != NET_XMIT_SUCCESS) { |
|
ret = NET_XMIT_DROP; |
|
goto put_primary_if; |
|
} |
|
|
|
frag_header.no++; |
|
} |
|
|
|
/* make sure that there is at least enough head for the fragmentation |
|
* and ethernet headers |
|
*/ |
|
ret = skb_cow_head(skb, ETH_HLEN + header_size); |
|
if (ret < 0) |
|
goto put_primary_if; |
|
|
|
skb_push(skb, header_size); |
|
memcpy(skb->data, &frag_header, header_size); |
|
|
|
/* Send the last fragment */ |
|
batadv_inc_counter(bat_priv, BATADV_CNT_FRAG_TX); |
|
batadv_add_counter(bat_priv, BATADV_CNT_FRAG_TX_BYTES, |
|
skb->len + ETH_HLEN); |
|
ret = batadv_send_unicast_skb(skb, neigh_node); |
|
/* skb was consumed */ |
|
skb = NULL; |
|
|
|
put_primary_if: |
|
batadv_hardif_put(primary_if); |
|
free_skb: |
|
kfree_skb(skb); |
|
|
|
return ret; |
|
}
|
|
|